"I'm sorry. I've been here since noon," the woman said with a smile, as a way to apologize for not hearing him.

"Well, I got to work at 5 this morning," the man snorted back.

I have more stress than you, he was saying. As a shopper in line behind him, I had fantasies of grabbing him to say that he, suit-clad man that he was, probably had a long day of thinking, meeting, sitting at a desk. Or maybe fighting a case in court or lobbying a politician to support whale-hunting interests in the Pacific Northwest. Stressful, sure. But meanwhile, this woman had been on her feet since noon, earning little and putting up with a lot -- like testy customers.

This man was her workplace stress.

Every job has a different kind of hair-pulling-out stress. But when customers take their rough day out on a person behind a cash register, that creates almost two full-time jobs for that worker: the first being the actual job, the second being the job of keeping even the unhappiest of people happy. That's not something, dare I say, that many people could do.

The folks at Whole Foods know that the exchange I witnessed is far from uncommon. They try to give workers ways to deal with grumpy customers and try to do things for the workers, who need to treat nasty customers with a smile. Much of the training focuses on "how not to take it personally," said Valerie McCausland, mid-Atlantic customer service coordinator for Whole Foods. "This was just something else in that gentleman's day, and she was the victim of his mood."

But how easy is it to just not take it personally? Or not catch that bad mood and take it home at the end of the day?